Delaminated containers are conventionally known that include a container body having an outer shell and an inner bag and having the inner bag delamination, with a decrease in contents, from the outer shell to be shrunk, and a check valve to regulate entrance and exit of air between an external space of the container body and an intermediate space between the outer shell and the inner bag (PTLs 1 and 2).
In PTL 1, a cap mounted to the mouth of the container body has a built-in valve.
In PTL 2, inside the main portion of the outer shell is equipped with a valve.